"MOVABLE POINT FOR A CROSSING FROG FOR RAILWAY APPARATUS OF VERY GREAT LENGTH, INCORPORATED IN LONG WELDED RAILS"

Abstract

The present invention relates to a movable crossing frog for apparatus of very great length, incorporated in long welded rails, said pint (7) being made of a single steel element. A movable point characterized in that it integrates seating cross members (8) and in that its rigidity is variable along all of its length from a minimum, adjacent its forward flexible portion (9), to a maximum, at its wide rear portion (10). The invention is particularly applicable to the field of the construction of railway equipment, particularly crossing points.

Full Text

The present invention relates to a movable point for crossing frog for railway apparatus of great length and more particularly, to the field of construction of railway equipment, particularly crossing frogs, and has for its object a movable point for crossing frog for railway apparatus of very great length, incorporated in long welded rails, said point comprising moreover arrangements to carry out its seating.
This type of crossing frog is known and its construction is described, particularly in EP-A-0 365 450. Moreover, FR-A-2 695 662 discloses the anchoring of such a crossing frog, which comprises a fixed portion, a cradle, and a movable portion, namely, the movable point.
Accordingly, there is provided a movable point for a crossing frog for railway apparatus of great length, incorporated in long welded rails, said point being comprised of a single molded steel element comprising a forward triangular monoblock portion, a central portion and a rear portion constituted by two elements to which are welded two rails forming a non-molded portion, the elements of the molded portion being shaped to the profile of the corresponding rail, characterized by only the front triangular portion being flexible and the central portion having integral laterally extending members for securement of said central portion.
According to this known construction, the movable point is comprised of rails machined and assembled and anchored at its heel in one of the elements of the cradle.
Other constructions of the point are known and are generally constituted, as shown in Figure 1 of the accompanying drawings, by a movable region located in front of the seat 1 and comprising two portions, namely a first portion 2, of substantially triangular shape, and a second portion 3 of two elements shaped as a rail profile. Such a point can be completely cast or comprised by three elements welded together.
In these known embodiments, the angle a of the point is relatively great and requires such a configuration. But when the angle a is
very small, the length of the assembly thus constituted becomes uselessly great, such that the movable region is practically limited to its triangular portion.
To this end, Figure 2 of the accompanying drawings shows at a, b and c the different known possible cross sections of the movable region, namely, at a, in the form of two rail profiles 4, at b in the form of a cast member 5 and, at c, in the form of a monoblock member 6.
Such sections have a high transverse moment of inertia which, on the one hand, involves large flexure forces, and on the other hand, does not permit adjustment of the curve of deformation of the point. Moreover, the construction of the seating requires a large number of pieces to connect the constituent elements of the point to the cradle.
The problem to be solved by the present invention is therefore to design and produce a movable point of a crossing frog which does not have these drawbacks.
To this end, the invention has for its object a movable point for a crossing frog for railway apparatus of very great length, incorporated in long welded rails, said point being comprised of a single steel element, characterized in that there are integrated therewith seating cross members and in that its rigidity is variable along all its length from a minimum adjacent its forward slender point, to a maximum at its wide rear.
The invention will be better understood from the description hereafter, which relates to a preferred embodiment, given by way of non-limiting example, and explained with reference to the accompanying schematic drawings, in which:
Figure 1 is a plan view of a mobile point of crossing frog of known type;
Figures 2a to 2c are cross-sectional views of various known modes of construction of the point;
Figure 3 is a plan view of a movable point according to the invention;
Figure 4 is a half view in cross section on the line C-C of Figure 3, of a seating cross member, and
Figures 5 and 6 are cross-sectional views of the movable point according to the invention, respectively on the lines A-A and B-B of Figure 3.
According to the invention and as shown more particularly by way of example in Figure 3 of the accompanying drawings, the movable point 7 for a crossing frog for railway apparatus of very great length, incorporated in long welded rails, which is produced from a single steel element, combines integrally seating cross members 8 and its rigidity is variable along all its length from a minimum adjacent its flexible forward portion 9, to a maximum at its wide rear portion 10.
The movable point 7 is essentially constituted by one piece, preferably of austenitic manganese steel and comprises a flexible forward portion 9, an inflexible central portion 11, bearing seating cross members 8, and a wide rear portion 10 constituted by two elements 10', to which are welded two rails 12 forming a portion 13, the elements 10' of the cast portion 7 matching the profile of the corresponding rail 12.
According to one characteristic of the invention, the movable point 7 is preferably one cast piece.
It is also possible to produce the movable point 7, according to another characteristic of the invention, by lamination and/or forging, followed by machining .
The flexible forward portion 9 comprises two regions of different cross section, whose general shape is that of an inverted T at its slender end 9' and of a I in its wider portion 9" connected to this slender end 9'.
According to one characteristic of the invention and as shown in Figure 4, the inflexible central portion 11 has a hollowed cross section.
The seating cross members 8, of which one is represented in detail in Figure 4 of the accompanying drawings, are present in the form of points of securement to a cradle 14 and are provided on opposite sides of the inflexible central portion 11.
Each cross members 8 comprises, on the one hand, at its end coacting with the cradle 14, a vertical plate 15 for bearing against the web of the cradle 14 and, on the other hand, vertical ribs 16 and a horizontal rib 17 for connection of each vertical plate 15 to the inflexible central portion 11 of the movable point 7.
Each horizontal rib 17 is provided, in line with the vertical plat 15 for bearing against the web of the cradle 14, with a recess 18 for the passage of a spacer ring 19.
Moreover, according to another characteristic of the invention, each vertical plate 15 for bearing against the web of the cradle 14 is provided with a metallic insert 20 of unalloyed steel, integrated into the plate at the moment of casting or mounting in this latter by force or welding. Such an insert permits obtaining a precise machining of the hole receiving a resilient pin 21.
Finally, according to another characteristic of the invention, the vertical wall 22 of the inflexible central portion 11 of the movable point 7 is provided, in line with each cross member 8, with a recess 23 permitting the passage of the head of a bolt 24 for securement to the cradle 14, at the time of its emplacement.
To ensure its emplacement on the cradle 14 and to limit the flexural forces, the movable point 7 should have certain characteristics of design seemingly incompatible, namely, it must be rigid in its slender end portion 9', and flexible in its wider portion 9". Such criteria can be satisfied by the inverted T shape of the portion 9' and the I shape of the wide portion 9", as shown in Figures 5 and 6.
As shown more particularly in Figure 5, the rigidity of the slender portion 9' is obtained by widening or thickening the foot 25 and by thickening the web 26. On the contrary, in its wide portion 9" (Figure 6), the foot 27 as well as the web 28 are thinned, and, in the portion nearest the seating, the width of the foot is reduced.
Modern CAO means permit easily determining the optimum dimensions of the movable point 7 according to the invention. To this end, a first computation is effected, permitting finding the moment of inertia of the various sections, to then calculate the curve of deformation of the point. According to the spacing from the desired curve, the parameters of the sections are modified and the computations are repeated. By successive approaches, the difference from the desired values is reduced. The deformation of the member is then effected to determine the stress distribution by structural computation. According to the results obtained, for example if it is determined that the stress concentrations are abnormal, the procedure is repeated to obtain an optimum result.
The movable point thus obtained can preferably be subjected to a cold peening operation by various known techniques, before placing it in service. The connection with the end rails is effected by welding according to known procedures, these rails being steel which has been treated or not.
Of course, the invention is not limited to the embodiment described and shown in the accompanying drawings. Modifications remain
possible, particularly as to the construction of the various elements or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

WE CLAIM:-
1. A movable point for a crossing frog for railway apparatus of great
length, incorporated in long welded rails, said point (7) being
comprised of a single molded steel element comprising a forward
triangular monoblock portion (9), a central portion (11) and a rear
portion (10) constituted by two elements (10') to which are welded
two rails (12) forming a non-molded portion (13), the elements (10')
of the molded portion (7) being shaped to the profile of the
corresponding rail (12), characterized by only the front triangular
portion (9) being flexible and the central portion (11) having
integral laterally extending members (8) for securement of said
central portion.
2. Movable point as claimed in claim 1, wherein said forward portion
(9) being flexible, and said central portion (11) being inflexible,
carry said seating cross members (8) and a wider rear portion (10)
constituted by two elements (10') to which are welded two rails (12)
forming a portion (13) which is not cast, the elements (10') of the
cast portion (7) matching the profile of the corresponding rail (12).
3. Movable point as claimed in claim 2, wherein the forward flexible
portion (9) comprises two regions of different cross section, whose
shape is that of an inverted T at its slender end (9r) and of an I in
the wider portion (9") connected to said slender end (9r).
4. Movable point as claimed in claim 2, wherein the inflexible central
portion (11) has a hollowed cross section.
5. Movable point as claimed in any one of claims 1 and 2, wherein the
seating cross members (8) are present in the form of securement
points to a cradle (14) and are provided on opposite sides of the
inflexible central portion (11).
6. Movable point as claimed in any one of claims 1, 2 and 5 wherein
each cross members (8) comprises on the one hand at its end
connecting with the cradle (14), a vertical plate (15) for bearing
against a web of the cradle (14) and, on the other hand, vertical
ribs (16) and a horizontal rib (17) for connection of said vertical
plate (15) to the inflexible central portion (11) of the movable point
(7).
7. Movable point as claimed in claim 6 wherein each horizontal rib
(17) is provided in line with the vertical plate (15) for bearing
against the web of the cradle (14) with a recess (18) for passage of
a spacing ring (19).
8. Movable point as claimed in any one of claims 6 and 7 wherein
each vertical plate (15) for bearing against the web of the cradle
(14) is provided with a metallic insert (20) of unalloyed steel,
integrated into the plate by casting or mounted in the latter
forcibly or by welding.
9. Movable point as claimed in any one of claims 2, 4 and 5 wherein
the vertical wall (22) of the inflexible central portion (11) of the
movable point (7) is provided in line with each cross member (8),
with a recess (23) permitting the passage of the head of a bolt (24)
for securing to the cradle (14), at the time of its emplacement.
10. Movable point for a crossing frog for railway apparatus of great
length substantially as herein described and with reference to the
and illustrated in the accompanying drawings 3 to 6.